An invention of Gudgeon (U.S. Pat. No. 6,066,807) describes a connector with several advantages relative to its prior art. Besides the ability to install it from the outside of an electrical work box as is done with other connectors, this connector can also be installed from inside the electrical work box by first threading it over the non-metallic electrical cable wires that had already been installed through the work box. This capability greatly reduces the labor involved in doing retrofit work on an existing wall installation. It eliminates the need for removing wall covering, such as sheetrock, to expose the exterior surface of the electrical work box so that a conventional connector can be installed, locked in place, and the cable properly clamped. Obviously, the wall would have to be patched after such an operation.
The connector of Gudgeon '807 is generally cylindrical and has a central orifice. It has a bullet shaped tapered nose at each end with a groove toward the center on either side of a center ridge. The outside diameter of the largest end (toward the center) of each nose piece is larger than the hole in the electrical work box for which it is designed. Typically, the electrical work boxes have either ½ inch or ¾ inch diameter holes, and the connectors are designed for use in either one or the other size.
The connector of Gudgeon '807 has a wide longitudinal slot which permits the resilient housing to be squeezed so as to enter the electrical box hole of a thin-walled electrical work box mounted internally inside of a building structure. The resilient housing is squeezed to then snap in place at the groove adjacent the central ridge for retention. Also, this connector of Gudgeon '807 has an integral self-adjusting wire clamp in the form of an angled member inside the central orifice. Wires from the non-metallic cable can enter through the connector of Gudgeon '807 only in the relative direction from outside the electrical work box inward since they are clamped and resist pull out in the opposite direction (but wires already in the work box can be threaded through a connector which is installed in the electrical work box hole from the inside).
However, the connector of Gudgeon '807 cannot be used with external (i.e. surface mounted on the exterior of a structure) electrical work boxes which have thicker walls and threaded holes, typically on even thicker bosses. The internal electrical work boxes have thin walls which fit in the grooves of the connector of Gudgeon '807 for a snap-in installation.